This is a research contract to established a clinical center to participate in a multicenter, randomized, double-blind, placebo controlled clinical trial that will assess the efficacy of minocycline in the treatment of rheumatoid arthritis (RA). The objectives of the proposed study are to determine whether minocycline is an effective therapy for the treatment of RA and to determine the frequency and severity of adverse effects of chronic minocycline therapy in patients with RA. Approximately 200 patients with RA will be randomized into an actively treated group that would receive a capsule containing 100 mg. of minocycline twice a day and a control group that would placebo capsules for one year. The primary measure of outcome will be an assessment of joint swelling and tenderness.